An algal species commonly known as didymo or “rock snot” has been found to be non-invasive after a collaboration between University of New Brunswick (UNB) graduate student Michelle Lavery and researchers from Queen’s University, l’Institut national de la recherché scientifique (INRS), and Brock University found remains in lake sediments dating back to 1970.

The discovery debunks the commonly held assumption that didymo—a nuisance algae that may threaten juvenile salmon because of habitat overlap—was introduced to different rivers in eastern Canada by humans. Now, it seems that didymo blooms may be linked to the effects of global climate change on aquatic ecosystems.

“Didymo has been present in the regional algal community for much longer than many people thought,” says Michelle Lavery, the study’s lead author. “Instead of human introduction, an environmental trigger is a more probable cause for its recent proliferation.” Lavery began this research at Queen’s as an undergraduate thesis student and is now completing her Masters at UNB’s Canadian Rivers Institute.

In response to the “human-transfer hypothesis,” several states in the U.S. banned felt-soled fishing boots, as it was believed these boots transferred didymo between rivers. While following gear-washing guidelines is still an advised best practice to prevent the spread of harmful aquatic species, in the case of recent didymo blooms from eastern Canada, other factors likely play a role in didymo’s unprecedented proliferation.

Didymo was first officially reported in the Gaspésie region of eastern Canada in 2006 and has now been observed in more than 25 river ecosystems. The algae grow in thick, woolly mats on the bottom of riverbeds and can have negative effects on the river flora and fauna.

The study suggests that climate warming, which accelerated in the region starting in the 1970s, may have created favourable conditions for the growth and spread of didymo.

“This is yet another example of the harmful effects of climate change,” says John Smol, biology professor at Queen’s and Canada Research Chair in Environmental Change. “Too much of any algae can be a problem. For areas in Quebec and New Brunswick that are world-renowned for recreational Atlantic salmon angling, didymo blooms may lead to undesirable ecosystem effects.”

This study was published in the Canadian Journal of Fisheries and Aquatic Sciences and was funded by the Atlantic Salmon Conservation Foundation and the Natural Sciences and Engineering Research Council of Canada.

To arrange a media interview, please contact Kelsey Seymour.

In the news

‘Rock Snot’ found to be native algae species in N.B. (CBC)

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